Seat track assemblies are commonly used for forward and rearward comfort adjustment of seat assemblies, particularly seat assemblies affixed in motor vehicles. Such seat assemblies normally have a seat base and a seat back, with the seat back pivotably connected to the seat base by a recliner. The seat base is commonly mounted over a pair of upper seat tracks which are in turn slidably mounted on a pair of lower seat tracks. The upper tracks are releasably secured together with corresponding lower tracks by a latch mechanism operable by a release lever, "towel bar" or other well known device. Such seat track assemblies used in motor vehicles are typically attached to a floor pan and optionally to side pillars, so that each lower track and other componentry rigidly attached to each lower track are fixed in position with respect to the motor vehicle. The upper tracks and the componentry mounted to them (that is, the seat cushion, etc.,) are adjustable to a range of fore-and-aft positions.
The upper and lower tracks are typically configured to be interlocked with each other so as to resist vertical separation, often with a reduced friction interface between them for ease of fore-and-aft position adjustment, such that the seat cannot be easily vertically dislocated from the lower tracks. Greater vertical dislocation forces may be experienced, however, than the interlocking tracks can withstand without unacceptable levels of permanent deformation or other damage. This is especially true for seat assemblies in which a seat belt system is mounted directly to the seat assembly, known as "all-belts-to-seat" designs, rather than to the side pillars or to the floor pan. U.S. Pat. No. 5,362,132, issued to Griswold et al, and U.S. Pat. No. 5,322,348 issued to Johnson illustrate the known approach of employing an exterior mounted J-hook fixed to a pair of interlocked seat tracks to secure a seat cushion frame to the lower track sub-assembly against upward dislocation forces. In normal operation, such J-hook is free to slide past an opposed J-hook or other flange fixed to the other one of the interlocking seat tracks during comfort adjustment. In the event of high vertical dislocation forces the seat cushion frame in such prior designs would lift only until the upper J-hook contacts its fixed counterpart. Thus, the J-hook arrangement enables the vehicle seat to withstand vertical dislocation forces beyond the level which can be withstood by the more lightly designed interlocking seat tracks.
While such known J-hook arrangements are useful in withstanding vertical dislocation forces, it has now been discovered that "peeling" can occur in response to high vertical dislocation forces. With a J-hook mounted on only one side of the seat track, the upper track can gradually bend laterally past the lower track in response to a high vertical dislocation force. Such deformation is typically permanent, and can render the seat track assembly inoperable.
In view of the foregoing, it is an object of the present invention to provide a seat track assembly with enhanced resistance to vertical dislocation forces, and in particular a seat track assembly which resists peeling. Additional objects and features of the invention will become apparent from the following disclosure and detailed description of various preferred embodiments.